1. Field of the Invention
The field of the present invention is liquid cooled electrodes, such as those used in glass melting furnaces.
2. Background
Glass is typically processed by heating and refining in batch within a melting furnace. Glass batches are typically heated from both flames from burners, which serve as the primary heat source, and from glass melt electrodes embedded in the wall of the melting furnace. The number of electrodes depends upon the size of the melting furnace and the characteristics of the glass being processed. These glass melt electrodes introduce additional thermal energy into the furnace by passing a current through the glass melt.
Current state-of-the-art glass melt electrodes use a two piece assembly, having a head, which is typically constructed from a refractory metal (such as molybdenum), affixed to a shaft cooled by an internal passage through which cooling water is passed. This shaft is often constructed from a variety of materials, such as stainless steel, a nickel based alloy, or even molybdenum. Such electrodes are disclosed in U.S. Pat. No. 3,983,309, U.S. Pat. No. 4,965,812, and U.S. patent application publication No. 20070064763. The disclosures of these documents are incorporated herein by reference in their entirety. Due to the high temperatures existing near the electrodes in the glass melt, a water-tight joint is difficult to achieve between the head and the shaft. Thus, the cooling passage is contained only within the shaft and cannot be extended into the head without compromising the durability of electrode under operating conditions.